Measuring Video Quality Using Partial Decoding

Abstract

The quality of video that is broadcast as a packet-based video stream is measured using decoded pictures in combination with information extracted from the transport stream and elementary stream layers of the packet-based video stream. The decoded pictures include selected frames and/or slices decoded from the packet-based video stream and are used to generate video content metrics. A composite score for the video quality can be generated from the video content metrics in combination with quality metrics of the transport stream and/or the elementary stream. If the composite score falls below a minimum score, a snapshot of the video is captured for later analysis.

1 . A method of measuring video quality, comprising the steps of:
 receiving a transport stream (TS);   parsing the TS to extract an elementary stream (ES) containing video packets;   extracting information from the TS and the ES;   partially decoding the ES;   generating video content metrics representative of the quality from the partially decoded video; and   generating a composite video quality score based on the video content metrics, and one or both of the TS information and the ES information.   
   
   
       2 . The method according to  claim 1 , wherein the ES information includes at least one of codec, bitrate, frame/slice/block types, block boundaries, and motion vectors. 
   
   
       3 . The method according to  claim 1 , further comprising the step of generating TS quality metrics from the TS information, wherein the composite video quality score is generated from the video content metrics and the TS quality metrics. 
   
   
       4 . The method according to  claim 1 , further comprising the step of generating ES quality metrics from the ES information, wherein the composite video quality score is generated from the video content metrics and the ES quality metrics. 
   
   
       5 . The method according to  claim 1 , further comprising the steps of generating TS quality metrics from the TS information and generating ES quality metrics from the ES information, wherein the composite video quality score is generated from the video content metrics, the TS quality metrics, and the ES quality metrics. 
   
   
       6 . The method according to  claim 1 , further comprising the step of decoding the ES, wherein the video content metrics are generated from the decoded ES. 
   
   
       7 . The method according to  claim 6 , wherein the ES is only partially decoded and the video content metrics are generated from the partially decoded ES. 
   
   
       8 . The method according to  claim 7 , further comprising:
 if any of the computed metrics exceeds a predefined threshold or the composite video quality score falls below a predefined threshold, storing a video snapshot generated from the partially decoded ES.   
   
   
       9 . The method according to  claim 8 , wherein the video snapshot comprises one of a thumbnail image, a few video frames, or a short part of the partially decoded ES. 
   
   
       10 . A method of measuring video quality, comprising the steps of:
 receiving a video stream;   partially decoding the video stream; and   generating video content metrics representative of the video quality from the partially decoded video stream.   
   
   
       11 . The method according to  claim 10 , wherein the video content metrics include at least one of blackout, jerkiness, blockiness, blur, and video freeze. 
   
   
       12 . The method according to  claim 10 , wherein the video stream comprises a packet-based video stream. 
   
   
       13 . The method according to  claim 12 , wherein the step of partially decoding includes decoding only I-slices of the packet-based video stream. 
   
   
       14 . The method according to  claim 12 , wherein the packet-based video stream includes compressed frames of multiple types and the step of partially decoding includes decoding only a subset of the multiple types of frames contained in the packet-based video stream. 
   
   
       15 . The method according  claim 10 , further comprising:
 if the video quality is determined to be poor, storing a video snapshot generated from the partially decoded video stream.   
   
   
       16 . The method according to  claim 15 , wherein the video snapshot comprises one of a thumbnail image, a few video frames, or a short part of the partially decoded video stream. 
   
   
       17 . A video distribution system, comprising:
 a video encoder for encoding a video stream;   a video decoder for decoding the video stream;   a plurality of video delivery nodes between the video encoder and the video decoder;   a first probe positioned between the video encoder and a first of the video delivery nodes; and   a second probe positioned between the last of the video delivery nodes and the video decoder,   wherein each of the first and second probes includes a partial decoder for partially decoding the video stream and is configured to measure video quality based on the partially decoded video stream.   
   
   
       18 . The system according to  claim 17 , further comprising additional probes in between the plurality of video delivery nodes, wherein each additional probe includes a partial decoder for partially decoding the video stream and is configured to measure video quality based on the partially decoded video stream. 
   
   
       19 . The system according to  claim 17 , further comprising a measurement correlation unit for collecting video quality measurements from all of the probes. 
   
   
       20 . The system according to  claim 17 , wherein each of the probes extracts transport layer information and elementary stream layer information from the video stream and measures video quality based on the partially decoded video stream, the transport layer information, and the elementary stream layer information.